Method and apparatus for making artificial stone



C. F. BARON Aug. 29, 1939.

METHOD AND APPARATUS FOR MAKING ARTIFICIAL STONE 1936 2 Sheets-Sheet 1Filed Nov. 18

INVENTOR Carol 1 75421) TTOQE EY C. F. BARON Aug. 29, 1939.

METHOD AND APPARATUS FOR MAKING ARTIFICIAL STONE Filed Nov.

, 1936 2 Sheets-Sheet 2 INVENTOR- Ccuoljffia 7 0/1 ATTORN Patented Aug.29 1939 UNITED STATES PATENT OFFICE ivmrnon APPARATUS FOR MAKINGARTIFICIAL STONE g 11 Claims.

This invention relates broadly to the art of making molded concreteblocks, such as are commonly used in the erection of buildings, and itdeals with the methods, as well as with the apparatus, employed in themanufacture of such blocks.

One object of the invention is: to provide an improved method formanufacturing concrete blocks, which method renders it unnecessary totouch the block from the time the concrete is poured into theblock-mold, to the time when the blocks are set and cured, and ready forthe builders use.

Another object of the invention is: to provide a simple and efiicientapparatus in/on which the blocks are formed or cast in molds and. maythere remain during further treatment and until finished, and then beremoved individually, one after another, and stored in close and compactformation. Referring to the apparatus specifically, so as to permit themanufacture and removal of the finished blocks along the lines indicatedabove, the invention provides a. plurality of ad- ,iaoentconcrete-receiving molds or receptacles separated from each other bycomparatively thin partitions which may be readily primarily assembledto form such receptacles, and which can be readily withdrawn ordisassembled to release the finished blocks, for removal.

Inasmuch as my improved method of making the blocks, and the apparatusfor doing so, are very closely allied with each other, and theirrelationship as to the position of the blocks on/in the apparatusremains the same throughout the entire process, the followingdescription of the invention will explain the entire process, step bystep, commencing with the primary building-up of the apparatus toprepare it for receiving the concrete mixture in the block-molds, andfollowing the successive steps required to produce the finished blocks,without, in the least, changing their positions in/on the apparatusduring that period, and finishing with the final taking down of thebuilt-up mold parts to liberate the finished blocks for removal andstorage.

Referring to the drawings:

Figure .l is a perspective View or the apparatus, the uppermost portionbeing partly broken-away 50 to disclose the molds filled with concretemix-.

ture.

Fig. 2 represents a side view of the apparatus, with the hood raised.

Fig. 3 is a cross section, on line 3-3 of Fig. 2,

55 the hood being down in operative position,

Fig. 4 is a longitudinal section, without the hood.

Fig. 5 is a plan view of the apparatus, with the molds in place, andcorresponding to Fig. 4.

Fig. 6 illustrates one step in building-up the 5 molds on the table.

Fig. 7 shows, in perspective view, one end of the frame which forms apart of and supports the hood fabric to form the curing chamber of theapparatus. 10

Fig. 8 illustrates a modification of the endclosing plate of the moldsto be used for forming full-length end-blocks, such as shown in Fig. 9.

Fig. 9 shows a full length end-block. 15

Fig. 10 shows a half-length end-block.

Fig. 11 is another modification of the endclosing plate, this speciesbeing adapted for making jamb-blocks, a full-length block being alsovshown in this figure. 20

Fig. 12 represents a half-length jamb-block, also produceable with theuse of the end-plate shown in Fig. 11. Rows of any of the types of theblocks just described may be cast at the same time with the regular wallblocks. 7 25 Fig. 13 represents a number of block-courses, sectionally,as they are built-up in horizontal for floors, or in vertical layers forWalls.

Fig. 14 shows, in perspective view, the manner in which staggered oroverlapping superposed 30 courses of blocks are laid, each course herehaving one end-block, one regular block, and one jamb-block to providefor a window or a door casing.

Fig. 15 is a perspective view of a regular block 35 provided with a.special facing applicable to the block while in process of manufacture.

In the manufacture of concrete blocks, it has been, and still is, commonpractice to cast a large number of such blocks at the same time on atable adapted to be transported immediately, after the molds are filledwith the desired concrete mixture, from this filling station to anotherlocation where the freshly-poured casts are subjected to specialtreatments, and thus permit another table with a new. set of molds to beplaced under the chute bringing the fluid concrete from the mixer.Ordinarily, each table is placed on, or forms a part of,.a car whichmust needs be strong enough to carry the weight and yet be easilymovable for travel, as for instance on rails which, however, inaccordance with my present invention, need not necessarily extend intoany building or chamber to bring the molds into locations for furthertreatment. In other words: the car may now be entirely in the open,because such enclosures, as are required to confine the molds fortreatment, may, in one aspect of my present invention, be applieddirectly to the car itself, in contradistinction to the usual manner ofrunning the car into one or more buildings or chambers built permanentlyand especially for that purpose.

The car, such as at present preferred, comprises a pair oflongitudinally-extending base-channel bars 26 supported by track wheels2| in any convenient manner. Extending laterally across the channels 20and supported thereby are a series of smaller channeled beams 22carrying the table plate 23 on which the block-molds are removably builtup into definite positions relative to each other, as follows:

The formation of the molds must, as a matter of course, conform to thetype of block to be made, the prefer-ably regular type being shown inFig. 6. This block B is substantially a rectangular parallelepipedhaving a centrally cored transverse hollow channel a extending throughit and at each end a semi-cylindrical groove b so that, when a series ofblocks are placed endto-end, each pair of adjoining grooves b will alsoform a cylindrical transverse passage similar to the channel a.Likewise, when a series of blocks are placed fiatwise and in overlappingor regularly-staggered courses, the channels a of one course and theend-grooves b of the adjacent course will be in alignment vertically orhorizontally, as the case may be, and form passages for ventilation orconduits for wires, pipes, etc. as may be desired when outfitting abuilding. Of course, it will be understood, that, when erecting abuilding, the adjoining blocks are to be united by a suitable cementbinder.

According to the present invention, the molds for the regular blocks arebuilt-up into composite formation by assembling a number of plates, ofwhich there are used three specific kinds, viz: partition-plates 25extending across the table, spacer plates 26 placed longitudinally ofthe table and between the partitions 25 to form rectangular boxes ormolds, and end-plates 21 which also extend across the table and arefirmly but removably secured to the table-top, (preferable bywithdrawable bolts or pins) and which, when so attached, will hold theentire assemblage firmly together, and against shifting on the table.

Considering first the end-platesZl, (see Figs. 1 to 4) they are formedof sheet metal and have their opposite ends attached, preferably byspotwelding, to angular reinforcing or stiffening strips 28, each havingat its lower end a perforated ear 28a to receive a lock pin 29 forsecuring that end of-the plate 2'! to the vertical leg of an L-shapedguide rail 39, two of such rails being provided and fixed to thetable-top near the side margins thereof, respectively, and so distancedfrom each other that the ears 28a will closely contact the inner facesof the rails 30. Each strip 28 has also an upper ear 28b to which issecured the upper end of a brace SI whose lower end is'detachably heldagainst the outer side of the rail 30 by alock pin 32, both pins 29 and32 preferably having eye-ends to facilitate their withdrawal, whenrequired. Inasmuch as the end-plates 28 and their attaching devices'areduplicates, and the extreme le'ngth of the endplates 28, as well asofthe partition-plates 25 is the same throughout the guide rails 30 areparallel and therefore hold those plate edges in properalignmentlongitudinally of the table; it

being understood, of course, that the plates are disposed at rightangles across the table and relative to the rails, see Fig. 4.

Considering next the partition-plates 25, these are similar in size andshape to the end-plates, excepting their end strips 28a which are herebent into U-form and do not have any holding ears. Attention is calledto the fact that the spaces between the inner edges of the two oppositestrips of each plate must be exactly the same to provide for properlyplacing the partition-plates so as to leave uniform block spaces betweenthem. Also, that the distance from each inner end-strip edge to theouter face of the strip-bend must be uniform, to insure parallelism ofthe guide bars withthe inner strip-edges to provide for proper locationof spacers 26.

The spacers 26 are merely plain thin sheet metal plates (see Fig. 6) allof which are exactly of the same size, so as to be interchangeable adlib., and which are interposed between the opposite faces of the severalpartitions and also their cooperative end-plates. As it is importantthat these spacers 26 must be equally distanced from each, across thetable, so that the widths of the molds for the cast blocks will all bethe same, means are provided on the partitions and on the working facesof the end-plates, for accomplishing that result, and, in accordancewith my present invention I make use of a row of cores C required toproduce the grooves 17 in the ends of the cast blocks B. In Figs. 1 and4 it will be seen that the table is here adapted to handle sixlongitudinal rows of blocks, each row consisting of seven blocks, makinga total of forty-two blocks for each setting. Therefore, six sets ofgroovecores are required on each of the two opposite contact faces ofeach partition, and, in order to produce the partitions as light inweight as possible, I preferably form all the cores C from thin sheetmetal intosemicylindrical shape provided with top and bottom attachingtabs 0 which latter may be spot-welded on the working faces of theseveral plates. The length of each groovecore is equal to the width ofthe block to be made, and the spaces between each adjacent pair of coreson the plate are equal to the thickness of the spacers which fit snuglybetween them and abut the working faces of the partitions. In otherwords: when a pair of cooperative spacers are properly engaging thepartitions between which they are located, there will be formed arectangular mold, whose end walls respectively have the cores necessaryto produce the end-grooves, b, b of the block B. Also, inasmuch as thespacerends contact firmly against the faces of the partitions, and thespaces which the plate-ends enter between the cores are equal to thethickness of the spacer-plates, it follows that, even if the cores Care, per se, open at both ends, yet there can be no leakage of concretemixture into the cores because the side face of the spacer-plates sealthem.

In Figs. 1 and 4, the partition-and-core combination has been clearlyillustrated, attention being now called to the fact that the upper andlower edges of the core-tabs do not extend to the upper and lower facesof the block, so that the full contour of the block-cast may bepreserved. On the other hand, the thickness of the tabs will naturallyleave a slight depression equal to their thickness in each end-face ofthe block, and for that reason I preferably feather the tabedges, toreduce and taper this depression in the manner shown. The sameconstruction applies to the cores C attached to the end-plates 21, onlyone set however being required for each end-plate.

When building-up the molds, one end-plate 21 being fixed in position,the first set of six spacers may be entered into the spaces between thecores C of the end-plates, whereupon the first partitionplate 28 is slidalong between the rails 30 until the still free edges of the spacers areentered into the spaces between the cores on. the partition and therecontact the face of the partition. The same operation is performed withthe second set of six spacers being entered between the cores C on theobverse face of the first partition, and the second partition isproperly located. It is evident that, if the end-plate 21 is disposed atright angles relative to the guide rails Sii, the partition-plates willalso be thus disposed, due to the fact, that the spacers are allinterchangeable and of exactly the same size. After the last set ofspacers has been placed, the final endplate is brought into engagementwith the still free spacer-edges and then locked by the insertion of thelock pins 29 and 32, thus providing, in the exemplary apparatus shown inthe drawings, a series of forty-two adjacent and interconnected molds,any pair of which are separated from each other across the table by onlyone member, viz.; one spacer-plate 26; and longitu:- dinally of thetable by a single partition-plate 25, features which are helpful andeconomical when screeding the concrete mixture in the molds, by a luteor similar device.

Referring again to the block B of Fig. 6, each of the molds assembled asabove described, takes care of a rectangular concrete-block as far asits general dimensions and the end-grooves, b, b are concerned. It,therefore, remains only to provide in the molds means for forming ineach block the interiorly-central conduit or channel a, so that, whenthe finished blocks are laid in overlapping courses when erecting abuilding, the conduit or of one layer or course will line-up withanother conduit formed by the combined semi-cylindrical grooves b, b ofany pair of adjoining blocks. For that reason, each spacerplate 26 has acentral aperture 26a of a diameter equal to that established by thecombination of the grooves b, b of the pairs of adjoining blocks, allthe apertures 26a of the spacers therefore becoming aligned and adaptedto receive a single core structure, such as 35, shown in Fig. 6andpreferably formed of a cylindrically-curled strip of sheet metalwhose outside diameter is substantially equal to that of the apertures26a, and whose length is sufficient to have its ends project (see Fig.4) slightly beyond the outer faces of last spacers for each transverserow of blocks on the table. The cores 35 are then pushed through thealigned spacer-apertures Zita, in which theyfit closely, and theirprojecting ends are then expanded, preferably by tapered plugs 35, so asto have a tight fit in the apertures of the outermost spacers of eachparticular row, and thus seal the molds against leakage. The insertionand endexpansion of the cores 35 constitute the final step building-upthe forty-two molds-of the apparatus, and they are now ready to receivesuch concrete mixture as may be commensurate with the requirements,directly from a mixer (not shown). If required by the nature of'theconcrete mixture, the table 23 may be equipped with a vibrator V (seeFig. 1) to agitate the mixture as it settles in the molds, and tothereby densify the cast, even before the curing operation is begun. I

In recapitulation be it stated that the abovedescribed manner ofbuilding-up the molds from pluralities of partition-plates 25, spacers26 and end-plates 21 respectively, is a simple process which, althoughpossibly requiring slightly more time in its accomplishment, whencompared with the time required for assembling a set ofindividually-separable molds, possesses the advantage that the entiremold outfit is light in weight, costs less in producing the necessarilylarge number of parts, eliminates waste of mixture due to screeding thecasts when the molds are filled, and also permits rapid removal of thefinished blocks, without any liability of damaging the finished blockfaces or corners by having them stick to the sides of preformed box-typemolds as used heretofore.

When all the molds arefilled from the mixer, the car may be rolled outfrom under the mixer or filling station to another nearby location wherethe casts are to be dehydrated and cured, a process which was heretoforegenerally carried out in an enclosed building or room where the castswere kept for a sufficient period, usually from one week to ten days, topermit the mixture to set or harden to a small extent before any actualheat was applied, during which setting period the casts were protectedfrom the direct rays of the sun and from drying winds, by covers ofcanvas, burlap, or sand.

In my improved method, I do not employ any coverings of any kind duringthe setting period, but allow the casts to harden or set naturally for aperiod of about one to two hours, according to atmospheric conditions, ashort period if temperature is warm, and a longer period if thetemperature is cold. The central cores 35 are then released by theremoval of the plugs 36, and withdrawn, leaving the central channels aopen and unobstructed from end-to-end, and ready for steam-curing, whichlatter is accomplished under a hood normally suspended in raisedposition and adapted to be lowered to entirely enclose the table top andthe filled molds supported thereon.

In conformity with my present invention, this hood and thesteam-supplying elements are combined into a single unit comprising aseries of bows H which are centrally spaced at the top on a tie-plate Hand whose opposite side ends H are substantially vertically parallel andare attached to nozzles N projecting toward each other from .a pair ofsteam-supply pipes 37, 38 which extend in parallelism with, and aresupported along, the sides of the mold-carrying table 23, respectively.The nozzles N of each pipe are so spaced longitudinally thereof that,when the pipes are placed into their positions on the table, theirrespective nozzles will be in alignment with and facing the outeropenings of the central channels a. At one or both ends of the car, thesteam pipes 3'! and 38 are rigidly connected preferably by pipes andfittings such as shown in Fig. 7, each of the connector branch pipes Ma,38a being provided with a valve 39, whereby the passage of superheatedsteam at about 250 F., supplied through a flexible steam-house 66, maybe regulated, as weather and temperature conditions may dictate toproduce the best results. From the foregoing it will be understood thatthe steam pipes and their associated bows and nozzles form a strongunitary frame which may be covered with canvas H over the top and ends,and whose side aprons h hang over and are adapted to entirely enclosethe sides of the molds on the table, and thus form a closed hood adaptedto be raised or lowered over the molds by a suitable tackle or crane(not shown) attachable to the hood at eye bolts, as shown. Inasmuch asit is necessary that the hood be properly located on the table so as tobring all the nozzles N into alignment with the cores a of the blocks,respectively, there are secured to the table top 23 a series of bracketsor stands 4| whose upper ends are bifurcated, as at Ma, to receive andsupport the side steam pipes 31, 38 at their required altitude above thetable-top, and also to act as side gages or stops to be contacted by theT-fittings such as 31b, 38b of the pipes 31, 38 respectively, to locatethe nozzles properly lengthwise of the table.

As shown, the top of the hood is crowned and located closely over thetops of the molds, a feature which maintains the emanating gases warmerand close to the product and also tends toward economy by theconservation of steam, the condensation of which will naturallyaccumulate on the underside of the canvas-covering and run off towardthe side aprons of the hood and to the table-top where it will undergomore or less of revaporization, according to the temperature of thetable .as produced by live steam issuing from the nozzles into the hood,and particularly into the open ends of the cored channels a, of eachtransverse row of block-casts. The steamjets are therefore projectedtoward each other, bringing their initial heat into direct contact withthe bare interiors or channels of the hollowed block-casts and therebyhastening the curing of the latter in a very substantial manner, fromthe inside of the cast toward the outside thereof. Furthermore, inasmuchas the several spacer-plates are made of metal, they will also becomehot, by virtue of the live steam coming into direct contact with theedges of the plate perforations 26a, and thus assist in dehydrating thecasts, especially at the side faces thereof, during the curingoperation, the latter taking only from four to eight hours, dependingupon the particular concrete-mixture and the latent heat of the vapor.

At the expiration of that period, the steamvalves are closed, and thehood is raised. The steam-cured casts and the molds are then to beexposed for gradually cooling-off and consequent contraction andresultant densification or hardening, this process requiring from one totwo days, depending upon the atmospheric conditions. Upon the conclusionof this curing period the molds .and blocks are taken apart, piece bypiece, and stacked, the blocks being then completely finished and readyfor immediate use.

When taking-down or disassembling the molds, one or both of end-plates21 are liberated by the withdrawal of the securing-pins 29, 32 andremoved from the table. The outer ends of the first row of spacer-plates26 will therefore be freed and may be pulled out to clear the sides ofthe blocks, without any liability of breaking or otherwise damagingeither the corners or faces of the blocks, the blocks being thereuponremoved from the table as fast as the spacer-plates 26 are taken out,that is to say: very speedily, as compared with the time required toslide finished cast blocks out of either unitary orindividually-assembled molds, with their accompanying danger of damagingthe cast blocks and thus causing waste of product.

The blocks which are to be cast on my improved apparatus can, of course,be any of the various types used in the erecting of buildings, all theblocks matching cross-sectionally but differing at their ends to meetdifferent purposes, as illustrated in Fig. 14. In Fig. 9 there is showna full-length terminal or end-block E such as may be used for floors orpartitions at their junctions with walls, etc., in which case thesemicylindrical groove 11 is dispensed with at one end, the block thenhaving a full face end I). The end-plate 21 against which those blocksare cast, should therefore not have any cores 0; so that other meanshave to be provided for properly spacing the end-edges of the last rowof spacerplates where they abut against the inner face of the end-plate.In the preferred form thereof shown, these means consist in forming thespacers 45 so as to have tabs 45a (see Fig. 8) projecting beyond theedge of the plates and adapted to enter slots 46 provided for them inthe end-plate 41 at proper distances between them. In Fig. 10 there isshown a half-length end-block Ea, having a plain end-face b, without anyend-groove, just like the full-length block E of Fig. 9. By referring toFig. 14 the utility of the half-length blocks Ea will be apparent, thelower layer or course L consisting of a full-length end-block E, aregular block B, and a half-length jambblock J a, the latter beingshown, per se, in Fig. 12, and having its end notched out at 7' toreceive the jamb or casing of a door or window. The next i andsuperposed layer or course I. consists here of a half-length end-blockEa, a regular block B, and a full-length jamb-block J, so that thevertical joints between the adjacent blocks of one course will be instaggered relation to the joint lines between the adjacent blocks of thenext course. The next superposed layer or course L will, of course, belike the course L the courses alternating as they are successivelybuilt-up, as is common practice.

From the foregoing description the necessity of providing half-lengthjamb-blocks Ja, will be evident, because the casing-receiving notches aof the superposed courses must be in vertical alignment, and match. Byreferring to Fig. 11 it will be noted that the notches :i are formed inthe blocks, J, Ja by substituting, on the inner face of the end-plate21, cores Co of rectangular form, for the semi-cylindrical cores C usedin the casting of the regular blocks B, it being understood that thecores Ca are spaced to closely receive the edges of the severalspacer-plates 26 of that row.

It is obvious that, while my invention has been fully explained by thedrawings and the description pertaining thereto, the showings are onlyof exemplary nature, especially in regard to the shapes and sizes of theblocks and the cores necessary to produce them; furthermore that copings, caps, sills and other building-elements can be economicallymanufactured by my improved method, with equal facility.

As to carrying out my improved method of manufacturing the blocks by theuse of the apparatus described, a brief and concise rsum of thesuccessive steps and the pertinent manipulation of the apparatus tocarry out those steps, may be in order to clarify the entire situation,from the time of building-up the molds to the time where the finishedblocks are removed, ready for use, as follows:

1. Build-up the molds, by assembling the end plates 21, partitions 25and spacers 26, and securing the end-plates 21 to the table rails 30 byusing the pins 29, 32. r

2. Place the long center-cores 35 into their positions by passing themthrough the apertures 26 of the spacers and so as to slightly projectbeyond the faces of the outermost spacers of each row, and drive-in theplugs 36, to make tight joints and prevent leakage of the fluid-mixtureof concrete toward the outside of the outermost molds.

3. Fill the molds, from the mixer chute, and screed their tops.

4. Clear the car from the mixer chute and bring it under the raisedhood, (which constitutes the curing station) to protect the molds fromdirect sun or rain.

5. Let the concrete set, while in the open, for a period of one to twohours, viz: a short period, if the atmosphere is warm, a longer period,if cold.

6. Remove the core plugs 36, and pull out the center-cores 35.

7. Drop the hood, to completely enclose the molds.

8. Open both steam-valves, to steam-cure the casts in the molds fromfour to eight hours, by injecting the steam into the centralcore-channels of the casts, bringing hot vapor into direct contact withthe now bare inside of the cast, and curing the latter from the inside,outwardly.

9. Shut-off the steam and raise the hood, letting the molds stand asthey are, for one to two days.

10. Take off the end-plates, upon withdrawal of the pins 29, 32.

11. Take the mold-plates and cast blocks apart, piece by piece, andstore them away for immediate or future use.

Considering the method involved, the total time actually used from thetime that the molds have been filled and screeded, need not exceed threedays, maximum which is a considerable saving over the period of from tendays to two weeks required heretofore.

Concerning the apparatus used, the molds can be quickly assembled andlocked to and on the table in predetermined positions, without bolts,screws, clamps, or tools. The hood is individual to any car, and can bequickly placed into correct position to line-up all the steam-nozzleswith the core-channels of the casts, without requiring adjustments ofany kind, either horizontally or vertically. The steam-supply can behandily regulated in accordance with the prevailing condition of theatmosphere, and can be readily dis connected when not needed, eitherfrom the hood itself, or by raising the hood from the table. Whendismantling the table, the mold-parts of each of the three types used(being exactly alike in shape and light in weight) can be easily stackedor stored in compact form.

It is sometimes desirable to make blocks which are coated at their upperfaces with a layer of hard veneer, to produce certain color efiects, andalso a hard wearing surface, especially when the blocks are to be usedfor flooring. Such a block is illustrated in Fig. 15, where the block Bhas a top-facing F which may consist primarily of a plastic compoundadapted to be spread over the exposed tops of the uncured concrete inthe molds, the concrete in that instance being screeded with a lute ofvariable depth to leave room for the veneering compound which then isscreeded level with the tops of the molds and is cured at the same timewith the concrete cast. In another instance ornamented or enameled tilesmay be applied to the tops of the cured concrete casts, a cement beingthen used for intimately binding the concrete block and its veneertogether, all while the casts are still in the molds.

It is obvious, of course, that variations and modifications may be madewithin the scope of this invention and portions of the improvements maybe used without others.

I claim:

1. A method of casting interiorly-channelled concrete blocks whichcomprises projecting jets of steam simultaneously into the opposite openends of the bare interior channel of each block and against the exteriorof the same to cure the block from the inside as well as the outside,and maintaining the warm steam in close proximity to and in contact withthe surfaces thereof to maintain the product and gases emanatingtherefrom at a uniform heat.

2. A method of casting and curing concrete blocks in a molding devicecomprising a plurality of molds having removable cores, the steps ofpouring the concrete to fill the molds and screeding the same, initiallysetting the blocks, removing the core from the molds, enclosing themolds with a means disposed in close proximity to the outer surfacethereof, and simultaneously projecting low pressure steam into thechannels formed in the concrete blocks by the removal of the cores andto the outer surface of the blocks so as to cure the blocks from theinside as well as from the outside, the steam being maintained inintimate engagement with the product by the enclosing means whereby theproduct and gases emanating therefrom are maintained at a uniform heat.

3. In a method of casting and curing concrete blocks in a molding devicehaving removable cores therein and a curing hood thereon, the steps ofpouring the concrete to fill the molds and screeding the same, producingan initial set in the blocks, removing the cores from the mold, loweringthe hood into position over the mold in close proximity to the product,and. forcing low pressure steam through the channelsformed in the blocksby the removal of the cores and also to the outer surface of the same tosimultaneously cure the blocks from the inside as well as from theoutside, the steam being maintained in close proximity with the productcausing a uniform heat to be-maintained on the product.

4. An apparatus for casting concrete blocks, comprising a table, aseries of adjacent molds arranged in longitudinal as well as intransverse rows and secured thereon, a hood movable to expose andcompletely enclose the table-top and said molds, and steam-supply pipessupporting said hood and having nozzles extending into the interiorthereof.

5. An apparatus for casting concrete blocks, comprising a table, aseries of adjacent molds arranged in longitudinal as well as intransverse rows and secured thereon, a hood movable to expose andcompletely enclose the table-top and said molds, steam-supply pipessupporting said hood and having nozzles extending into the interiorthereof, and devices secured to the tabletop for positioning said steampipes on the table to bring said steam-nozzles into predeterminedpositions relative to said molds, and simultaneously position said hoodover said molds.

6. An apparatus for casting concrete blocks, comprising a table, aseries of adjacent molds arranged in longitudinal as well as intransverse rows and secured thereon, a hood vertically movable'to exposeand completely enclose the tabletop and said molds, and steam-supplypipes supporting said hood at the outer sides thereof and having nozzlesextending through the sides of said hood into the interior thereof.

7. An apparatus for casting centrally-channeled concrete blocks,comprising a table, a series of adjacent molds arranged in longitudinalas well as in transverse rows and secured thereon, a hood movable toexpose and completely enclose the table-top and said molds andsteam-supply pipes supporting said hood and having nozzles extendinginto the interior thereof and adapted to project steam-jets into saidchannels formed in the blocks in the molds, respectively, at theopposite open ends thereof.

8. An apparatus for casting centrally-channelled blocks comprising atable; a series of adjacent molds arranged in longitudinal as well astransverse rows and secured thereon; a hood movable to expose andcompletely enclose the table and said molds; and a steam supply pipesupported on said hood and having nozzles extending into the interiorthereof and adapted to simultaneously project steam jets into the openends of said channels formed in the blocks in the mold and to the freeexterior surfaces of said blocks to thereby cure the concrete from theinside as Well as from the outside.

9. An apparatus for casting centrally-channelled blocks comprising atable; a series of adjacent molds arranged in longitudinal as Well astransverse rows and secured thereon; a hood movable to expose andcompletely enclose the table and said molds; and a steam supply pipehaving nozzles extending into the interior of the hood to simultaneouslyproject steam jets into the open ends of said channels formed in theblocks in the mold and to the free exterior surfaces of said blocks tothereby cure the concrete from the inside as Well as from the outside.

10. A method of casting and curing concrete blocks in a molding devicecomprising a plurality of molds having removable cores, the steps ofmolding the blocks and initially setting the same; baring the interiorof the block by removing the cores from the molded blocks; andprojecting low pressure steam into the interior of the blocks and intoengagement with the outer surface thereof to cure the blocks While theyare still in the molds.

11. A method of casting and curing concrete blocks in a molding devicecomprising a plurality of molds having removable cores, the steps ofmolding the blocks; forming channels extending through the molded blocksby removing the cores; simultaneously projecting low pressure steam intothe open ends of each channel and into engagement with the bare interiorof the blocks; and maintaining the steam in intimate engagement with theouter surface of the blocks to cause a uniform heat to be maintainedthereon and the product cured simultaneously from the inside and outsideWhile in the molds.

CAROL F. BARON.

